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Sea-Level-Rise Scenarios

The VIMS report on recurrent coastal flooding uses 4 scenarios of sea-level rise for planning purposes. The scenarios were developed for the National
Climate Assessment and modified for southeastern Virginia by incorporating an estimation of
land subsidence in the region. The 4 scenarios represent
plausible trajectories for local sea level based on a combination of
factors:

The “low” scenario is
based on the IPCC 4th Assessment model using conservative assumptions
about future greenhouse gas emission (the B1 scenario).

The
“high” scenario is based on the upper end of projections from
semi-empirical models using statistical relationships in global
observations of sea level and air temperature.

The “highest” scenario is based on
estimated consequences from global warming combined with the maximum
possible contribution from ice-sheet loss and glacial melting (a
practical worst-case scenario based on current understanding).

The science
team that developed the scenarios for the National Climate Assessment
indicated the high scenario should allow assessment of risk from limited
ice-sheet loss, while the low scenario represents risk primarily from
ocean warming. Recent data suggest that sea-level rise is currently proceeding along the
“high” trajectory. For planning purposes the VIMS report recommends anticipation of a 1.5-foot rise in sea level above the 1992 datum within
the next 20 to 50 years (2033 - 2063).